Role of Preoperative Serum Thyroglobulin Level to Differentiate Between Different Thyroid Nodules

Incidence of thyroid nodules varies according to the methods of diagnosis, 4-7% by palpation and 17-67% by high resolution ultrasound.

The gold standard of diagnosis for thyroid nodules is fine needle aspiration (FNA); however, fine needle aspiration cytology (FNAC) alone is insufficient to detect cancer because of inadequate cytology (5-15%) and in cases of follicular neoplasm (15-25%) where only surgery is diagnostically conclusive. Therefore, other factors in addition to FNA should be considered to predict malignancy. This study is done to evaluate the association between elevated pre-operative thyroglobulin levels and histopathologically proven thyroid carcinoma.

Metabolism of thyroglobulin occurs in the liver and via thyroid gland and recycling of the protein takes place. Circulating thyroglobulin features a half lifetime of 65 hours. Following thyroidectomy, it will take many weeks before thyroglobulin levels become undetectable. After thyroglobulin levels become undetectable (following thyroidectomy), levels are often serially monitored.

A subsequent elevation of the thyroglobulin level is an indicator of recurrence of papillary or follicular thyroid carcinoma. Hence, thyroglobulin levels in the blood are mainly used as a tumor marker for certain kinds of thyroid cancer (particularly papillary or follicular thyroid cancer). Thyroglobulin is not produced by medullary or anaplastic carcinoma.

Therefore, this study tries to evaluate the association between the preoperative thyroglobulin levels and thyroid carcinoma proven by post-operative histopathology.